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North Sea Network Interconnector, UK and Norway [free access]

November 8, 2021

Developers: National Grid Electricity Transmission plc (NGET) of UK and Statnett of Norway

 

Project details and status: The recently commissioned ±500 kV, high voltage direct current (HVDC) North Sea Network Interconnector is the world’s longest subsea electricity cable. The 720-km-long project connects Kvilldal in Norway to Blythe in the UK. Statnett and National Grid conducted a feasibility study in 2009 and confirmed the economic and technological feasibility of this 1.4 GW interconnector, approximately 340 km of which is in UK waters.

 

MMT, a Swedish marine survey company, was awarded a contract in March 2012 for conducting a route survey for the project. In June 2012, Statnett and National Grid signed an agreement confirming their plans to build the interconnector.

 

The Norwegian portion of the interconnector was approved by the Ministry of Petroleum and Energy in October 2014. The Northumberland County Council approved the route for the land portion of the UK segment of the interconnector.

 

In December 2014, Office of Gas and Electricity Markets (Ofgem) launched a consultation process for the construction of the interconnector, and UK’s Marine Management Organisation (MMO) approved the subsea route for the UK segment.

 

In March 2015, Statnett and National Grid signed the ownership agreement in Oslo.

 

In July 2015, equipment majors Nexans S.A., ABB and Prysmian were awarded the contract to construct the NSN interconnection. France’s Nexans was to design, manufacture and install a major section of the interconnector on the Norwegian side under a EUR340 million contract; Italy’s Prysmian would supply and install around 950 km of submarine and land cables in two sections (totalling 470 km in route length) under a contract worth EUR550 million; while ABB was to install HVDC converter stations at either end of the line under a USD450 million contract.

 

In March 2017, Parsons Brinckerhoff, a US-based construction and engineering company, was awarded a submarine contract for undertaking the cable manufacturing quality and inspection services for the project.

 

In July 2017, Prysmian PowerLinkS.r.l subcontracted Canyon Offshore Limited, a subsidiary of the US-based Helix Energy Solutions Group, for cable trenching services on the 1.4 GW link.

 

In July 2020, NGET and Statnett reported that the project had reached the halfway point. The next step of the project was to lay the cable from the fjords in Suldal to the North Sea.

 

In August 2020, Netherlands-based offshore and onshore geotechnical and survey services company Fugro completed a contract for the French cabling solution provider Nexans, for providing remotely operated vehicle (ROV) survey and monitoring support services to lay the North Sea Link (NSL) cable.Fugro disclosed that it reinforced the two cables’ installation through a mountain (between Hylsfjorden and Lake Suldalsvatnet) and along a lakebed, at a depth of 210 m, in Norway.

 

The final stretch of the cable was joined in early June 2021 on a cable-laying vessel almost 465 km from Blyth and 150 km from Stavanger in Norway. Consequently, testing commenced with low-voltage settings. The tests were initially conducted up to 700 MW capacity in June and July 2021and at full capacity of up to 1,450 MW from August 17, 2021.

 

The project was commissioned in October 2021.

 

The total value of the project is estimated at USD2.1 billion.

 

(EUR1=USD1.16)